In patients with haemophilia, repeated bleeding events result in significant comorbid conditions that can degrade health-related quality of life. Clinician-reported symptom measures are available for use in patients with haemophilia A or B; however, there has not been a validated patient-reported symptom evaluation instrument available for haemophilia to date. The objective of this study was to develop and evaluate a self-report instrument, the HAEMO-SYM, for measuring symptom severity in patients with haemophilia. Eighty-four haemophilic subjects from Canada and the USA were enrolled and completed the HAEMO-SYM, SF-36, and Health Assessment Questionnaire-Functional Disability Index (HAQ-FDI). Four-week reproducibility was evaluated in 72 stable subjects. Construct validity was assessed by correlating subscale scores with the SF-36, HAQ-FDI, a coping questionnaire and clinical scores. The final 17-item HAEMO-SYM has two subscales: pain and bleeds. Internal consistency reliability was good (Cronbach's alphas, 0.86-0.94) and test-retest reliability was good (Intraclass Correlation Coefficients, 0.75-0.94). HAEMO-SYM subscale scores were significantly correlated with SF-36 scores (P < 0.05 for all except HAEMO-SYM Pain and SF-36 Mental Health), HAQ-FDI scores (P < 0.05 for all but HAEMO-SYM Bleeds with HAQ-FDI Hygiene and Reach), Gilbert scale (P < 0.01), coping (P < 0.05) and global pain (P < 0.001). Mean HAEMO-SYM scores varied significantly in groups defined by severity, HIV status and treatment regimen. Greater symptom severity was associated with more severe disease, HIV-positive status and prophylaxis treatment. The results of this study suggest that the HAEMO-SYM, a haemophilia-specific symptom severity instrument, has good reliability and provides evidence that supports construct validity in patients with haemophilia.